The invention relates generally to a high-pressure transducer to be mounted in a mounting hole in a component, consisting of a sensor joined to the transducer body and having a diaphragm and an arrangement for sealing the transducer against the mounting hole.
The invention relates especially, though not exclusively, to pressure transducers for detecting high pressures at elevated temperatures, as are encountered typically when the transducer is used in combustion engines, for ballistic pressure measurements or in plastics injection molding.
The main problem is the sealing of the transducer against the mounting hole, which calls for the application of considerable sealing forces. These affect the sensor element and may be detrimental to its sensitivity. Known are transducers (EP-A-90 871 and 90 872) which can be fitted in the mounting hole to seal either at a shoulder surface or front end surface. Further examples of sealing at shoulder surfaces include U.S. Pat. Nos. 3,857,287; 4,399,706; 4,519,254 and 4,735,091. A further example of a sealing at a front end surface includes U.S. Pat. No. 4,559,821.
Thus, it is an object of the present invention to create a pressure transducer which can be sealed both at a shoulder surface and a front end surface.
Another object is to provide a single pressure transducer which is capable of being sealed at shoulder surfaces and front end surfaces of mounting holes.
These objects are achieved, according to the present invention, by a transducer body having sealing arrangement including both a shoulder sealing surface and a front end sealing surface. According to a preferred development of the invention, the shoulder sealing surface may be provided at an intermediate section of the axial extent of the transducer body with an integral shell part of enlarged diameter, which can be made to seal against a shoulder offset surface of a mounting hole. The front end sealing surface is provided on an integral tubular extension at the front end of the transducer body. In order to isolate the force flow lines essentially from the sensor when using the shoulder sealing to seal the transducer, an annular gap can be provided between the sensor and the transducer body. The effects on the sensor of the force flow lines occurring in front end sealing are circumvented or alleviated, by providing an elastic front connection between the transducer body and sensor isolate.
The transducer body may be mounted to a mounting hole by a thread section, which preferably is between the intermediate section and the front end or by an externally threaded retainer which engages a retainer surface of the intermediate section.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.